Chapter 2 - Page 49

Any clairvoyant or fortune-teller will make cunning use of the Barnum effect to dupe credulous punters.

This is not surprising: people have been found to be more accepting of generalised feedback than actual, factual feedback (Merrens and Richards, 1970).

A study of 68 personnel managers in the 1950s highlights the way in which we can accept the most vague statements about our personality as reflecting reality.

Stagner (1958) administered personality tests to these managers and gave them 13 bogus statements that were assumed to represent actual feedback about their personality from the tests (e.g., 'You have a great need to people to admire or like you' and 'You have a tendency to be critical of yourself.').

When asked to rate how strongly the participants agreed with these statements, almost all indicated that they believed them to some extent and one-third regarded their profile as a 'good' reflection of their character.

For some statements such as, 'You prefer a certain amount of change and variety...' and 'While you have some personality weaknesses...', over 80 per cent of participants expressed agreement with them.

In an ingenious spin on the Barnum phenomenon, Furnham (1994) set up an experiment in which undergraduates gave samples of their hair to an experimenter.

A week later the participants were given a 'trichological analysis' - 24 bland statements regarding their health based on the hair sample - that was totally bogus.

Most students thought that these randomly applied statements were very accurate.

What does research on the Barnum effect tell us?

First, it shows us that most individuals are inclined to accept bland feedback about themselves

Secondly, it shows us that the validity of a test involves more than intuitively 'knowing' that a test measures something.

Most individuals - unless they knew about the Barnum effect - would have regarded the statements at the beginning of this section as true and might have accepted the statement that intelligent but sceptical readers are drawn to boxed-off areas of textbooks.

This statement is, of course, nonsense.

Thirdly, and perhaps most importantly, the Barnum effect shows us that we should always adopt a sceptical and questioning approach to statements made about human behaviour - even to this last statement.